What is an affiliate and how do they make money?

Affiliate marketing is the method by which an affiliate earns a commission for marketing another person's or company's products or services. An affiliate merely searches for a product they enjoy, applies to become an affiliate with that person or company, then promotes and markets that product or service and earns a piece of the profit from every sale they make. That was the short answer. For a more in-depth answer, read this pdf article I discovered.